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<title>16.16 commands -- Utilities for running commands</title>
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<h1><a name="SECTION00181600000000000000000">
16.16 <tt class="module">commands</tt> --
         Utilities for running commands</a>
</h1>

<p>
<a name="module-commands"></a>  
<p class="availability">Availability: <span
 class="platform">Unix</span>.</p>

<p>
The <tt class="module">commands</tt> module contains wrapper functions for
<tt class="function">os.popen()</tt> which take a system command as a string and
return any output generated by the command and, optionally, the exit
status.

<p>
The <tt class="module">subprocess</tt> module provides more powerful facilities for
spawning new processes and retrieving their results.  Using the
<tt class="module">subprocess</tt> module is preferable to using the <tt class="module">commands</tt>
module.

<p>
The <tt class="module">commands</tt> module defines the following functions:

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-3623' xml:id='l2h-3623' class="function">getstatusoutput</tt></b>(</nobr></td>
  <td><var>cmd</var>)</td></tr></table></dt>
<dd>
Execute the string <var>cmd</var> in a shell with <tt class="function">os.popen()</tt> and
return a 2-tuple <code>(<var>status</var>, <var>output</var>)</code>.  <var>cmd</var> is
actually run as <code>{ <var>cmd</var> ; } 2&gt;&amp;1</code>, so that the returned
output will contain output or error messages. A trailing newline is
stripped from the output. The exit status for the command can be
interpreted according to the rules for the C function
<tt class="cfunction">wait()</tt>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-3624' xml:id='l2h-3624' class="function">getoutput</tt></b>(</nobr></td>
  <td><var>cmd</var>)</td></tr></table></dt>
<dd>
Like <tt class="function">getstatusoutput()</tt>, except the exit status is ignored
and the return value is a string containing the command's output.  
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-3625' xml:id='l2h-3625' class="function">getstatus</tt></b>(</nobr></td>
  <td><var>file</var>)</td></tr></table></dt>
<dd>
Return the output of "<tt class="samp">ls -ld <var>file</var></tt>" as a string.  This
function uses the <tt class="function">getoutput()</tt> function, and properly
escapes backslashes and dollar signs in the argument.
</dl>

<p>
Example:

<p>
<div class="verbatim"><pre>
&gt;&gt;&gt; import commands
&gt;&gt;&gt; commands.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
&gt;&gt;&gt; commands.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
&gt;&gt;&gt; commands.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
&gt;&gt;&gt; commands.getoutput('ls /bin/ls')
'/bin/ls'
&gt;&gt;&gt; commands.getstatus('/bin/ls')
'-rwxr-xr-x  1 root        13352 Oct 14  1994 /bin/ls'
</pre></div>

<p>
<div class="seealso">
  <p class="heading">See Also:</p>

  <dl compact="compact" class="seemodule">
    <dt>Module <b><tt class="module"><a href="module-subprocess.html">subprocess</a></tt>:</b>
    <dd>Module for spawning and managing subprocesses.
  </dl>
</div>

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